This section introduces aspects that may be helpful to facilitating a better understanding of the inventions. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.
Conventional dense wavelength-division multiplexing (DWDM) systems typically have a grid spacing of about 50 GHz. While this spacing has been sufficient for many purposes, increasing demand for more customers/channel, greater reach and greater capacity are expected to exceed conventional grid capacity.